Chemical mechanical polish pad conditioning device

ABSTRACT

A chemical mechanical polish pad conditioning device is disclosed. The device includes a conditioning substrate made of stainless steel forming a predetermined pattern on a surface. Also, a method of producing a chemical mechanical polish pad conditioning device is disclosed. The method includes providing a conditioning substrate made of stainless steel forming a predetermined pattern on a surface, and applying a hardening process to the surface of the conditioning substrate. The invention further discloses a method of conditioning a chemical mechanical polish pad. The method includes providing a conditioning substrate forming a predetermined pattern on a surface, fixing the conditioning substrate to a conditioning arm, and contacting the surface of the conditioning substrate with a polish pad and moving the conditioning substrate on the polish pad with a predetermined downforce at a predetermined rate of speed. Because the conditioning substrate does not use a diamond layer bonded to the substrate, there is no risk that detached diamonds may become embedded in the polish pad in the course of polishing. Under the configurations of the conditioning device, production of a custom conditioning device that meets specified cut-rate or surface roughness specifications can be achieved

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of application Ser. No. 09/751,910 filedon Dec. 20, 2000.

BACKGROUND OF THE INVENTION

[0002] Chemical Mechanical Planarization (CMP) is a technology used insemiconductor wafer fabrication to achieve sub-micron features. CMP isused to planarize the surface of a wafer after a deposition process hasbeen performed. FIG. 1 shows a side view of a conventional waferpolishing apparatus (2). In FIG. 1, a semiconductor wafer (10) issecured to a carrier (12). In order to polish or planarize the wafer(10), the surface of the wafer (10) adjacent to pad (14) is forceddownward by carrier (12) against the top surface of the pad (14). Bothwafer (10) and pad (14) with attached table (16) are rotated withrespect to each other to planarize the surface of the wafer (10). Aslurry is deposited or pumped on the pad (14) through pipe (18) to aidin the polishing of wafer (10).

[0003] One, of the most critical steps in the CMP process isconditioning of the polish pad surface. Most pads in use today aremanufactured from a thermoset plastic such as polyurethane. The pad mustbe conditioned to get rid of the process affluents and to maintain aprecise profile so that planarization occurs in the desired window.Without conditioning, the pad would clog up with process affluents andthe profile would change due to the downforce used in the CMP process.Some manufactures use in-situ conditioning, while others use a serialconditioning process. In either case, the conditioning cycle must occur.

[0004] A diamond-coated substrate is a popular choice among current CMPconditioning elements. The diamond-coated device is affixed to aconditioning arm or fixture and moved across the polish pad at apredetermined rate of speed and downforce. This allows the user tocontrol the profile of the pad and to remove a minute portion of thesurface thus eliminating the affluents from the previous process cycle.However, in some cases, the torque created by this conditioning processcauses diamonds to be pulled from their glue layer and become embeddedin the polish pad. During the next planarization cycle, the embeddeddiamond may scratch the wafer causing the wafer to be irreparablydamaged.

SUMMARY OF THE INVENTION

[0005] In general, in one aspect, the present invention relates to achemical mechanical polish pad conditioning device which comprises aconditioning substrate made of stainless steel forming a predeterminedpattern on a surface thereof.

[0006] In general, in one aspect, the present invention relates to amethod of producing a chemical mechanical polish pad conditioning devicewhich comprises providing a conditioning substrate made of stainlesssteel forming a predetermined pattern on a surface thereof, and applyinga hardening process to the surface of the conditioning substrate.

[0007] In general, in one aspect, the present invention relates to amethod of conditioning a chemical mechanical polish pad which comprisesproviding a conditioning substrate forming a predetermined pattern on asurface thereof, fixing the conditioning substrate to a conditioningarm, and contacting the surface of the conditioning substrate with apolish pad and moving the conditioning substrate on the polish pad witha predetermined downforce at a predetermined rate of speed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a side view of an example of a wafer being polished witha polishing pad in accordance with the prior art.

[0009]FIG. 2 is a perspective view of an embodiment of the presentinvention.

[0010]FIG. 3 is a plan view of a patterned conditioning substrate inaccordance with an embodiment of the present invention.

[0011]FIG. 4 is a plan view of a patterned conditioning substrate inaccordance with an embodiment of the present invention.

[0012]FIG. 5 is a plan view of a patterned conditioning substrate inaccordance with an embodiment of the present invention.

[0013]FIG. 6A is an expanded plan view of pyramid shaped patterns formedon a portion of a conditioning substrate in accordance with anembodiment of the present invention.

[0014]FIG. 6B is a cross sectional view of the pyramid shaped patternsshown in FIG. 6A cut by the line I-I thereof.

[0015]FIG. 7 is a plan view of a template of the patterned conditioningsubstrate, which is used to form patterns on the surface of thesubstrate in accordance with an embodiment of the present invention.

[0016]FIG. 8 is a sectional view of the conditioning device inaccordance with an embodiment of the present invention.

[0017]FIG. 9 is a table showing a comparison of cut-rate of aconditioning device of an embodiment of the present invention versus adiamond coated conditioning device.

DETAILED DESCRIPTION

[0018] The present invention relates to a conditioning device for a CMPpolishing pad which can achieve a precise profile of the CMP polishingpad without using abrasive particles, such as diamonds. The presentinvention addresses production of custom-patterned conditioningsubstrates in accordance with desired cut-rate or surface roughnessspecifications. Referring to the drawings, wherein like elements aredescribed by like reference numbers throughout, embodiments of thepresent invention are explained as follows.

[0019]FIG. 2 shows a perspective view of an embodiment of the presentinvention. A holder mechanism (28) includes a conditioning arm (29) andbase (26). A bottom surface of the base (26) is provided with aplurality of grooves (27) which are used to flow adhesives therein. Theconditioning substrate (24) is made of metal having sufficient hardness,such as stainless steel. A plurality of diamond patterns (30) are formedon the bottom surface of the conditioning substrate (24). When used tocondition the polishing pad, the conditioning substrate (24) is attachedto the bottom face of the base (26) and the patterned bottom surface ofthe conditioning device (4) is contacted with the polish pad. It is alsopossible that the conditioning substrate (24) be fixed to theconditioning arm (29) by using two-sided tape or a magnet without usingthe base (26).

[0020] FIGS. 3-6 show alternate patterns and shapes of the conditioningsubstrate (24). These patterns act as abrasive elements while in contactwith the polish pad. FIG. 3 shows a diamond pattern formed on thesurface of the conditioning substrate (24) in a radial manner from acentral point. FIG. 4 shows a diamond pattern formed on the conditioningsubstrate (24) in a similar but more densely distributed manner. FIG. 5shows a ring-shaped conditioning substrate (24) with diamond patternsthereon. The patterns are formed on the bottom surface of theconditioning substrate (24) by using chemical etching process. A desiredpattern can be created using a CAD drawing of the pattern, which is thenused to create the etched template (36) as shown in FIG. 7. By doingthis, it is possible to precisely control the pattern and thereforecontrol the amount of polish pad removed for a given time and downforce.These patterns can also be formed by using casting, forging, ormachining processes. However, the chemical etching process is generallypreferred because it can offer more time and cost-effective productionthan forging or machining.

[0021] With respect to the design of the patterns, circular, triangular,spiral, or pyramid pattern may also be employed other than the diamondpattern. FIG. 6A shows a partially expanded plan view of the pyramidshaped pattern formed on a conditioning substrate. FIG. 6B shows a crosssectional view of the same cut by the line I-I of FIG. 6A. This pyramidpattern can be effectively formed using a machining process. Althoughany of these patterns can be used for producing the conditioningsubstrate, the diamond pattern is generally preferred because it canallow more latitude in adjusting the removal rates than other patterns.

[0022] Once formed, the patterned surface of the conditioning substrate(24) is treated to increase the hardness of the substrate by a hardeningprocess, for example, an ion-nitride treatment process. Using theion-nitride treatment process, the hardness of the surface of theconditioning substrate (24) can be increased by approximately 20 pointsof Rockwell hardness. Because the ion-nitride process does not applyextremely high temperature to the substrate, the flatness of thesubstrate can be maintained at about 12.5 m. A common method used forhardening stainless steel is to heat treat a steel component to adesired temperature and then gradually cool the piece down. However,such high heat treatment may cause the substrate be warped and, as aresult, the flatness of the conditioning substrate in relation to thepolishing pad would be deteriorated.

[0023]FIG. 8 shows a sectional view of a conditioning device (4) of anembodiment of the present invention. The conditioning substrate (24) isadhered to the bottom of the base (26) at the grooves (27), which arefilled with adhesives, such as chemically resistant two-part epoxy.Because the adhesive used for adhering the conditioning substrate (24)flows evenly in the grooves (27), the conditioning substrate (24) can beadhered to the bottom of the base (26) in a highly flat manner inrelation to the base (26). It is, of course, possible to attach theconditioning substrate (24) to the base (26) by using other mechanicalmeans, such as screws. However, because of the strict flatnessrequirement between the conditioning substrate (24) and the base (26),such means significantly increase the complexity of joining the twoparts.

[0024] The base (26) with attached conditioning substrate (24) issecured by the holding mechanism (28), which includes conditioning arm(29). Under this configuration, the chemical mechanical polish padconditioning device (4) is contacted with the surface of the polish padby a downforce transmitted through the conditioning arm (29) and rotatedexactly horizontally on the polish pad with a predetermined downforceand at a predetermined rate of speed. By this operation, theconditioning device (4) can effectively eliminate the process affluentsfrom the previous cycle at a high cit-rate.

[0025]FIG. 9 shows a comparative table wherein cut-rate performance ofthe conditioning device of an embodiment of the present invention and anelectroplated diamond coated conditioning device are compared.

[0026] For comparing the cut-rate performance, a stainless steelconditioning substrate ring having 25.40 cm outside diameter and 20.32cm inside diameter and an industry standard electroplated diamondconditioning ring having the same outside and inside diameter wereprepared. The stainless steel substrate ring was provided with diamondpatterns on its bottom surface by using a ferric chloride etchingprocess. The substrate was then treated with an ion-nitride hardeningprocess to obtain a hardness of RC 40. The stainless steel conditioningsubstrate and the electroplated diamond conditioning device wererespectively fixed to a base element which is connected a lappingmachine to conduct this test. The test was performed using an IC 1000pad on a Lapmaster lapping machine. The cut-rate was obtained bymeasuring the pad before and after the conditioning by the conditioningsubstrates. All tests were performed using 67 static pounds of downforceon the rings. Each test cycle was 15 minutes. For charting purposes, theaverage cut-rate over a three-hour interval was plotted.

[0027] Initial cut-rate data was obtained using the diamond-conditioningring. The stainless steel patterned conditioning substrate ring was thenemployed with cut-rate data recorded in 15-minute intervals forforty-five hours. The diamond-conditioning ring was then run followingthe stainless steel ring substrate test.

[0028] As can be seen from the table, the results of the test indicatesthat the removal rate attained by the stainless steel patternedconditioning substrate is comparable to that which has been achieved bythe diamond conditioning device.

[0029] Advantages of the present invention may include one or more ofthe following. In one or more embodiments, because the conditioningsubstrate does not use a diamond layer bonded to the conditioningsubstrate, there is no risk that detached diamonds may become embeddedin the polish pad in the course of polishing. Because the surface of theconditioning substrate is kept extremely flat in relation to thepolishing pad, a precise profile of the polish pad can be achieved byusing the conditioning device of an embodiment of the present invention.Also, because the etching pattern can be created on an etch templateusing CAD system, it is possible to precisely control the pattern andtherefore control the amount of polish pad removed for a given time anddownforce. Because the conditioning substrate can be adhered to the basein a very flat manner, the conditioning substrate can be maintained flatin relation to the polishing pad. As a result, even polishing of the padcan be achieved. Given the configurations of the conditioning devicedescribed above, production of a custom conditioning device that meetsspecified cut-rate or surface roughness specifications can be achieved.

[0030] While the present invention has been described with respect to alimited number of preferred embodiments, those skilled in the art willappreciate numerous modifications and variations therefrom. The appendedclaims are intended to cover all such modifications and variations whichoccur to one of ordinary skill in the art.

What is claimed is:
 1. A chemical mechanical polish pad conditioningdevice, comprising: a stainless steel conditioning substrate having apredetermined pattern formed on a surface thereof.
 2. The deviceaccording to claim 1, further comprising: a base; wherein theconditioning substrate is fixed in flat relation to the base.
 3. Thedevice according to claim 2, wherein a surface of the base is providedwith a plurality of grooves and the conditioning substrate is adhered tothe base by an adhesive placed in the grooves.
 4. The device accordingto claim 1, wherein a hardening process is applied to the surface of theconditioning substrate.
 5. The device according to claim 4, wherein thehardening process is an ion-nitride treatment process.
 6. The deviceaccording to claim 1, wherein the pattern on the surface of theconditioning substrate is formed by a chemical etching process.
 7. Thedevice according to claim 1, wherein the pattern on the surface of theconditioning substrate is formed by a casting process.
 8. The deviceaccording to claim 1, wherein the pattern on the surface of theconditioning substrate is formed by a forging process.
 9. The deviceaccording to claim 1, wherein the pattern on the surface of theconditioning substrate is formed by machining.
 10. The device accordingto claim 1, wherein the pattern on the surface of the conditioningsubstrate is formed in a diamond shape.
 11. The device according toclaim 1, wherein the pattern on the surface of the conditioningsubstrate is formed in a circular shape.
 12. The device according toclaim 1, wherein the pattern on the surface of the conditioningsubstrate is formed in a triangular shape.
 13. The device according toclaim 1, wherein the pattern on the surface of the conditioningsubstrate is formed in a spiral shape.
 14. The device according to claim9, wherein the pattern on the surface of the conditioning substrate isformed in a pyramid shape.
 15. A method of producing a chemicalmechanical polish pad conditioning device, comprising: forming apredetermined pattern on a stainless steel conditioning substrate.applying a hardening process to the surface of the conditioningsubstrate.
 16. The method according to claim 15, further comprisingfixing the conditioning in flat relation to a base.
 17. The methodaccording to claim 16, disposing a plurality of grooves in a surface ofthe base; and adhering the conditioning substrate to the base by anadhesive placed in the grooves.
 18. The method according to claim 15,wherein the hardening process is an ion-nitride treatment process. 19.The method according to claim 15, further comprising: the pattern on thesurface of the conditioning substrate by a chemical etching process. 20.The method according to claim 15, further comprising: the pattern on thesurface of the conditioning substrate by a casting process.
 21. Themethod according to claim 15, wherein the pattern on the surface of theconditioning substrate is formed by using a forging process.
 22. Themethod according to claim 15, further comprising: forming the pattern onthe surface of the conditioning substrate by machining.
 23. The methodaccording to claim 15, further comprising: forming the pattern on thesurface of the conditioning substrate in a diamond shape.
 24. The methodaccording to claim 15, further comprising: forming the pattern on thesurface of the conditioning substrate in a circular shape.
 25. Themethod according to claim 15, further comprising: forming the pattern onthe surface of the conditioning substrate in a triangular shape.
 26. Themethod according to claim 15, further comprising: forming the pattern onthe surface of the conditioning substrate in a spiral shape.
 27. Themethod according to claim 22, further comprising: forming the pattern onthe surface of the conditioning substrate in a pyramid shape.
 28. Amethod of conditioning a chemical mechanical polish pad, comprising:forming a predetermined pattern on a surface of a conditioningsubstrate; fixing the conditioning substrate to a conditioning arm;contacting the surface of the conditioning substrate with the polishpad; and moving the conditioning substrate on the polish pad with apredetermined downforce at a predetermined rate of speed.
 29. The methodaccording to claim 28, further comprising: fixing the substrate in flatrelation to a base connected to the conditioning arm.
 30. The methodaccording to claim 29, further comprising: providing a plurality ofgrooves in a surface of the base and adhering the conditioning substrateto the base by an adhesive placed in the grooves.
 31. The methodaccording to claim 28, further comprising: applying a hardening processto the surface of the conditioning substrate.
 32. The method accordingto claim 31, wherein the hardening process is an ion-nitride treatmentprocess.
 33. The method according to claim 28, further comprising:forming the pattern on the surface of the conditioning substrate by achemical etching process.
 34. The method according to claim 28, furthercomprising: forming the pattern on the surface of the conditioningsubstrate by a casting process.
 35. The method according to claim 28,further comprising: forming the pattern on the surface of theconditioning substrate by a forging process.
 36. The method according toclaim 28, further comprising: forming the pattern on the surface of theconditioning substrate by machining.
 37. The method according to claim28, further comprising: forming the pattern on the surface of theconditioning substrate in a diamond shape.
 38. The method according toclaim 28, further comprising: forming the pattern on the surface of theconditioning substrate in a circular shape.
 39. The method according toclaim 28, further comprising: forming the pattern on the surface of theconditioning substrate in a triangular shape.
 40. The method accordingto claim 28, further comprising: forming the pattern on the surface ofthe conditioning substrate in a spiral shape.
 41. The method accordingto claim 36, further comprising: forming the pattern on the surface ofthe conditioning substrate in a pyramid shape.